Fixed #16863 -- Corrected ReST markup to avoid errors building docs.

Although directives such as "note" and "warning" will accept content
immediately following the directive, this is technically where arguments to the
directive should go (see http://sphinx.pocoo.org/rest.html#directives). Putting
the content there means that any lines beginning with an inline text role
(e.g. ":setting:`DEBUG`") will be mis-interpreted as an option block for the
directive. To avoid this error, there should always be a blank line between the
directive start and the directive content.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@16842 bcc190cf-cafb-0310-a4f2-bffc1f526a37